Conversion of hydrocarbons in presence of carbon tetrachloride and the halides, bromine and iodine



Feb. 25, 1947. Q FOLKlNs ETAL 2,416,660 CONVERSION OF HYDROCARBONS IN PRESENCE OF CARBON TETRACHLORIDE AND THE HALIDES, BROMINE AND IODINE Filed Feb. 9, 1944 2 Sheets-Sheet l N-BUTANE DECOMPOS\T\ON AT 525'C PERCENT PRESSURE INCREASE .u .o,wa aazaasaza8 l2 5 A- 5 6 7 s 9 10 u I2 \5\4l5|6 NIB \9 2021 22232425 TIME (MINUTES) INVENTORS Fi n HiI/Lis 0. Fol/kins Ca/PL isl/e M Thaoker ATTORNE Y 1947. H. o. FOLKINS ET AL 2,415,660 CONVERSION OF HYDROCARBQNS IN PRESENCE OF CARBON TETRACHLORIDE AND THE HALIDES, BROMINE AND IODINE Filed Feb. 9, 1944 2 Sheets-Sheet 2 N-BUTANE DECOMPOSITION AT 500C PERCENT PRESSURE INCREASE F3 6 ra I z a 4 5a 7 a 9 IO u 12 I3l4 1516 \I \819202122232425 TIME (MINUTES) INVENTORS Fig 2 Hill/is O.F0Lkins aa z'llisbe M Tluwkel' BY i mx H. 12W,

AT TORNE Y Patented Feb. 25, 1947 CONVERSION OF HYDROCARBONS IN PRES- ENCE OF CARBON TETRACHLORIDE AND THE HALIDES, BROMINE AND IODINE Hillis 0. Folkins, Skokie, and Carlisle M. Thacker. Highland Park, Ill., assignors to The Pure Oil Company, Chicago, 111., a corporation oi. Ohio Application February 9, 1944, Serial No. 521,596

. Claims.

This invention relates to conversion of hydrocarbons and is more particularly concerned with a method for converting higher boiling hydrocarbons into lower boiling hydrocarbons and for making unsaturated hydrocarbons from saturated hydrocarbons.

We have discovered that if thermal conversion of hydrocarbons is carried out in the presence of a small amount of carbon tetrachloride admixed with a small'amount of bromine or iodine or both. the cracking of the hydrocarbon is greatly accelerated so that it is possible to obtain larger yields of cracked hydrocarbons under the same time-temperature-pressure conditions than it is possible to obtain in thermal cracking of the hydrocarbons without sensitizer, and it is possible to obtain yields at lower temperatures which are commensurate with yields obtainable at higher temperatures without sensitizers. Our invention is applicable to either branch or continuous methods of cracking. In continuous cracking methods by operating under usual thermal cracking conditions in the presence of a sensitizer, not only can increased yields be obtained but higher octane gasoline can be produced. By using a sensitizer, a larger through-put oi charging stock through a given size unit can be effected because of the acceleration in the cracking reaction caused by the sensitizer.

An object of our invention is to provide a method for conversion of hydrocarbons.

Another object of our invention is to provide a method for accelerating cracking of hydrocarbons.

Still another object of our invention is to provide a method for increasing octane number of motor iuel made by cracking of hydrocarbons.

A further object of our invention is to provide a sensitizer which will accelerate the decomposition of hydrocarbons.

A still further object of our invention is to provide a method for improving thermal cracking of hydrocarbons.

Other objects of the invention will become apparent from the following description and the accompanying drawing, of which Figure I is a graphical representation ofdata showing the unexpected results obtained under certain conditions using sensitizers in accordance with our .chloride andthe halogen may be mixed with the hydrocarbons prior to charging them to the reaction zone or they may be injected directly into the reaction zone. The total sensitizer mixture may be used in concentrations from approximately .055 mole percent to 5 mole percent based on the total charge and should contain not less than about .005 mole percent of bromine and/or iodine, and not less than about .05 mole percent of carbon tetrachloride. Higher concentrations of sensitizers may be used, but within the limits above set forth the reaction progresses rapidly without causing accumulation of undesirably large amounts of the sensitizers and their decomposition products in the motor fuel or other product which it is desired to produce. In our ex? perimental work we have found that a mixture containing from .03 mole percent of bromine up to 2 mole percent of bromine and from .25 percent of carbon tetrachloride up to 2 percent of carbon tetrachloride gives unusually good results.

Our invention is useful in conjunction with conventional types of thermal cracking in which the hydrocarbons are cracked at temperatures within the range of approximately 375 C. to 750 C. and is applicable to conversion of hydrocarbon gases such as propane and butane as well as to the conversion of liquid hydrocarbons such as heavy naphtha, kerosene and gas oil. The combination of thebromine and/or iodine with carbon tetrachloride accelerates the cracking reaction to an extent far in excess of that which would be expected from the additive effect of the carbon tetrachloride and the bromine or iodine alone. In order to demonstrate this fact a number of runs were made using normal butane as charging stock. The butane had a purity of 99%. The runs were all made in a Pyrex glass reaction vessel at temperatures either of 500 C. or 525 C. Before starting each run the reaction vessel was heated to the desired reaction temperature and then evacuated by means or a vacuum pump to a pressure below 0.001 mm. of mercury. Suilicient butane in admixture with the desired amount of sensitizer composition was then charged to the evacuated vessel until the pressure in the vessel approximated atmospheric pressure. The reaction was permitted to proceed in the closed reaction vessel while the temperature was maintained either at 500 or 525 C. until a pressure increase of 25 percent above the initial pressure was observed, whereupon the reaction gases were rapidly removed from the reactor and analyzed. In some runs where the acceleratlon in reaction was extremely rapid the pressure increase somewhat exceeded 25 percent before the reaction was terminated.

A number of runs were also made without any sensitizer and other runs were made using Only carbon tetrachloride and only bromine as sensitizer.

Data for runs made at 525 C. is tabulated in Table I. Runs made at 500 C. are tabulated in Table II, In each of the runs the initial pressure was calculated, a pressure reading was made 0.5 minute after the run began, thereafter pressure readings were made at intervals of 1 minute from the beginnin of the run until 6 minutes thereafter, from that point readings were made at 2 tained from recorded data by linear interpolation.

In the table the figures given under the heading Time in minutes for AP of 25%" are in some cases recorded and in other cases are interpolated from curves based on recorded pressures because in certain runs the pressure rose above 25% increase too rapidly to obtain a reading at the exact point.

The sensitization factors recorded in the tables are obtained by dividing the time required for a particular pressure increase without sensitizer, by the time required for the same pressure increase with sensitizer. By referring to Tables I and II it is evident that carbon tetrachloride alone accelerates the decomposition of butane. Compare, for example, runs 43, 44 and 45 with the average for runs 38, 39, 42 and 46. Bromine likewise considerably accelerates the cracking of the butane as is evident from a comparison of the blank runs and those experiments made with bromine alone'in Tables I and II. However, when carbon tetrachloride and bromine were used together the rate of acceleration greatly increased. For example whereas 0.5 mole percent of bromine alone gave a sensitization factor of 7.3 (run 49) and 0.5 mole percent of carbon tetrachloride gave a sensitization factor of 3.7 (run 44), 0.5 mole percent of carbon tetrachloride together with 0.5 mole percent of bromine gave a sensitization factor of 44 (run 52) for a 25% increase in pressure.

In order to demonstrate that this remarkable increase in acceleration of thereaction is greater than the additive effect of the twosensitizers, curves were plotted for a number of runs based on the pressure increases recorded at the aforesaid intervals during the run. The curves were plotted with time in minutes as abscissae and percent pressure increase as ordinates.

, Referring to Figure I or the drawing, curve .1

is the curve for the average of blank runs 47,151 and 57. Curve 2 is based ,on the data recorded for run with carbon tetrachloride present in the amount of 0.25 mole percent. Curve 3 is the plot of data for run with bromine present in an amount of 0.25 percent, Curve 5 is obtained from data recorded during run with both carbon tetrachloride and bromine present in amounts of 0.25 mole percent. Curve 4 represents the hypothetical or additive results which would be expected from using together .25 mole percent of carbon tetrachloride and .25 percent bromine. It is obtained by adding at selected time (from curve 1) the pressure increase caused at the same time by the presence of carbon tetrachloride alone (curve 2 minus curve 1) and the pressure increase caused at the same time by the presence of bromine alone (curve 3 minus curve 1), and plotting on the graph the figures obtained for a. different number of different time periods to be able to draw a curve through the points. As an example, referring to Figure I, at a time 2.8 minutes after the run began the pressure increase without any sensitizer, obtained from curve 1, is 5.7. At the same time the pressure increase for carbon tetrachloride alone is 12.5 (obtained from curve 2) and the pressure increase for bromine alone is 18.5 (obtained from curve 3). The pressure increase due to the presence of carbon tetrachloride is therefore 12.5 minus 5.7, or 6.8. The pressure increase due to the presence of bromine is therefore 18.5 minus 5.7, or 12.8. The pressure increase that might be expected from the combination of carbon tetrachloride and bromine at the time of 2.8 minutes is the sum of the pressure increase at the same time without sensitizer and the pressure increases caused by each of the sensitizers, or 5.7 plus 6.8 plus 12.8 or 25.3 percent pressure increase. By referring to curve 4 it will be seen that 25.3 pressure increase is obtained after 2.8 minutes.

Comparing this with the actual experimental result obtained it will be seen that only 0.8 minute was required to obtain a pressure increase of 25%. Thus the actual acceleration and reaction is more than three times as great as would be expected from the additive effect of the carbon tetrachloride and bromine. In terms of sensitization factor at 25% pressure increase at a temperature of 525 a mixture of .25 mole percent of carbon tetrachloride and .25 mole percent of bromine gives a sensitization factor of 27.5 as against an expected additive sensitization of 8.

Figure 11 is a similar graph showing the actual efiect of decomposition of normal butane at 500 C., using a mixture of 0.25 mole percent of carbon tetrachloride and 0.25 mole percent of bromine (run 77).

Data similar to those obtained on runs 55 and 77 were obtained and the results tabulated in Table III in order to show a comparison between the time actually required to obtain an increase in pressure of 25% and the time which would have been expected from the additive effect. The

comparable sensitization factors are also recorded.

A number of runs were also made in a.continuous laboratory cracking apparatus using gas oil from Pennsylvania Crude as charging stock.

As an example, a run was made charging 1.004 gallons per hour of gas oil containing 0.1% by weight of bromine and .25 percent by weight of carbon tetrachloride, The mixture was sub- The nature of the reaction products reaction. is essentially the same with or without sensitizer. The invention is useful in connection with known types of mineral oil thermal cracking without catalyst. It is also useful in catalytic cracking operations wherein a known solid comminuted catalyst, such as natural or synthetic alumina-silica compositions, is used. The invention may also be used in connection with cracking -as cracking of propane to ethylene. cracking or butane to ethylene and propylene or the cracking of liquid hydrocarbons to oleflns or diolefins such as butadiene.

10 of gases to make unsaturated hydrocarbons, such Table I A yield of 21.7

F. E. P. gasoline, havingan ocwas obtained whereas when It will be apparent from the analysis of reac- Wfl 3 0 9 6 h n n a n w a a Mm n a n P n H m m mO A A n n t m u n n n M m 6 5 0 M 95.01.40.000 5 0 2 .o 2 8 2 7 1 4 67 m n1m m nmnmwnmuunnnnnnnnwmwm e R n R l I m H o u s 4 4 4 6 7 u 4 5 29s 6 d H 0 0 0 d H 0000000L0 0 0 0 0 0 0 0 0 0 1.0 0 1 u u u M O m 4 J 1 M n 2311211030 0 0 0 2 2 3 2 21111 n. 0 n C n 0 0 0 M C 0000000000 0 0 0 0 0 0 0 00000 0 0 w m 6 .o 4 m a 0502801331 7 4 0 0 5 0 7 0344 0 t m m mam m a aaaaaaauamnmmmmunmmmnm n U n U M m 0 0 2 s 0 0 0 0 0 2 00 0 0 0 0 0 0 0 2 0 20000 n 0 0 0 M 0000000000 0 0 0 0 0 0 0 00 0 0 0 A n A m A m f c sfi t tt m 2 m awz m a m mm w ucvwuunaua m Mm m J 0 8 Mm 08858019 2 2 0 3 2 0 1 4 7073 2 o mm m m awn I ma m uw mwwumummmm m S 1. S8 1 0.- I me! e S m 6 6 R kw m 7 0481270 0 0 .0 .o 0 0 7 4.5771 1 1 9 t n 221 .w 5 mmmmmauanmmnunu m T o u m w w a mflnwmwmwu w W m w w M w wwwwm s 5 a 0 0 r m 2 u m n filfn QHfil 1 1 1 1 1. 1 2 omwwa u u .m 7 m m w 2 w o M%%mwmflm& m w w H m H M w m wa M P 5 P 5 .mA u 0 0 0 .mA 2 v 247122410 0 0 0 0 0 0 0 049ml 1 1 r. Br mm mm 0 2 .l a m 5 T amfififi 5 n 0 0 0 0 5 011100000 0 0 0 0 0 0 0 m 0 0 Ll 0 t 5 5 555 .m m mttestasteee .m m momma .mttt r. 1 1... 10000000000 m 100210020000000LLQ200210LLfiQQQQ a m m m a W .1 t H m s u a u m u n n u s e n h e a n n n n n m n s m a n "0 a L L N N n rCrC H none I\ mm m m m m M "wnmw m m 4. n um. 7 n 1 m n r n p I n 0 a M m m m m m wwm M m H 4 N jected to a temperature or 475' C.- and a pressure of 500 pounds per square inch.

percent of 400 tane number of 60 the gas oil was cracked under the same conditions 5 without the presence of any sensitizer the yield of gasoline was 17.5% by volume and the octane number was 55.3.

tion products in Tables I and II that the reaction is primarily one of splitting of the carbon to carbon bond as shown by the relatively large amount of unsaturated hydrocarbons formed and the small amount of hydrogen formed in the Table I1! Bensitizer gffi g gg ?:312'??? Run Temp., MAP No. O.

m seeaze- 11.2-

55 fish: 8 525 0.8 2.s 27.5 8.0 52 g2: 3 525 0.5 1.5 44.0 14. 7 52 gs 8:? 525 0.6 1.2 36.1 11.6 54...... 382: 3:3 525 0.0 2.0 36.7 11.0 77 3g; 3 500 2.1 7.2 25.1 2.9 -68 ESE: 8:2 500 1.5 4.5 47.5 14.8

78 83k: {:3 500 0.5 3.0 89.0 23.7 60 3}: 8:? 500 1.0 5.8 37.5 12.3 72 32: 13 500 1.5 4.8 47.5 i 14.8 75...... 32: 1:3 500 1.6 4.1 44.5 17.4 70 2; 8 500 1.8 6.8 39.6 12.3 73 g2; g g 500 1.5 4.0 47.5 1 17.8 74 335;; 5g, 500 1.3 as 64.8 25.4 83 g3}: 3:8 500 5.4 215 13.2 8.4

the halogen is bromine.

3. Method in accordance with .claim 1 in which the carbon tetrachloride is present in the mixture undergoing conversion in amount of at least .05 mole percent and the halogen is present in amounts of at least .005 mole per cent.

4. Method in accordance with claim 1 in which the minimum amounts of carbon tetrachloride and halogen in the mixture undergoing cone 5. The method of cracking hydrocarbons having at least 3 carbon atoms in the molecule which comprises heating said hydrocarbons to .a, tem-. perature of approximately 375 C. to 750 c.;1n j;- the presence of a mixture of carbon tetrachloride and bromine, the carbon tetrachloride being present in the total mixture undergoing con-J version in an amount not less than about .05 1 mole percent and the bromine being present-in? an amount not less than about .005 mole percent.-

6. Method in accordance with claim 5 in'which; the cracking is carried out in' the substantial;

absence of other cracking promoters. I

'7. Method in accordance with claim 5 in which 1 the maximum combined amount of carbon tetrachloride and bromine present is 5 mole percent.-

a large portion of propane. 9. Method in accordance with claim 5 in which the hydrocarbons subjected tocracking comprises a large portion of butane.

10. Method in accordance with claim 5 in which v the hydrocarbons are composed chiefly of hydrocarbons boiling above the gasoline boiling range.

HILLIS 0. FOLKINS.

CARLISLE M. THACKEB.

REFERENCES CITED The following references are of record in the J file of this patent:

UNITED STATES PATENTS- in the mix-' 

